People protect themselves against heavy air pollution on Jan. 16 in Beijing. China's capital was shrouded in thick smog, cutting visibility as small particulate pollution climbed to more than 24 times the recommended safety level. Wang Zhao, AFP/Getty Images

Thick smog shrouds skyscrapers in Tianjin, China. Air pollution soared over the World Health Organization's safety level, forcing officials to close schools and order cars off the roads. Diego Azubel, epa

A woman wearing a face mask walks along a street in Beijing. Wang Zhao, AFP/Getty Images

Thick smog covers a main road in Beijing. A law proposed by the Ministry of Environmental Protection wants to make local governments responsible for implementing pollution control measures. Rolex Dela Pena, epa

Air pollution masks a view of the city as a woman walks across an overpass. Wang Zhao, AFP/Getty Images

People wear masks as they walk on a street in Beijing. Rolex Dela Pena, epa

Tourists in masks use mobile phone cameras to snap shots of themselves during a heavily polluted day on Tiananmen Square in Beijing on Jan. 16. Beijing's skyscrapers receded into a dense gray smog as the capital saw the season's first wave of extremely dangerous pollution, with the concentration of toxic small particles registering more than two dozen times the level considered safe. Alexander F. Yuan AP